Break up with a friend?

I am thinking of breaking my friendship with a friend who i have known for almost 8-9 years. She is bipolar and i am having a hard time with her. she says she doesn't care as much as i do. i asked if i could go visit her she said no. we have a friends wedding coming up and so i asked if i could get a ride in her care and i would pay for gasoline. for that too she said no because she has to go see her family in that state after the wedding. recently again she is wanting to go to PA and see a friend there. since she does not have railway station in her hometown, i asked her to come to my town to catch a train. she says no not there. how should i feel or what are your thoughts on this. Is it time to let go of this friend or keep her? she does not want to talk much to me at this time. please help